Probiotic Weissella cibaria KY10 derived from digestive tract of healthy shrimp exhibits strong antibacterial effects against Vibrio parahaemolyticus causing AHPND in shrimp

The antibacterial activity of Weissella cibaria KY10 derived from digestive tract of healthy shrimp was investigated against Vibrio parahaemolyticus T.11 causing AHPND. In the co-cultivation assay, W. cibaria KY10 completely inhibited the growth of V. parahaemolyticus T.11 at 12 h under aerobic conditions. The antibacterial substances produced by W. cibaria were detected by GC-MS in parallel to the morphological changes of treated Vibrio cells. The major antibacterial components were higher-pKa acids, such as propionic, acetic, succinic and palmitic acids. Other minor antibacterial compounds included 4-ethenyl-2,6-dimethoxy, 5-oxo, 2-methoxy-4-vinylphenol, 2,5-dimethoxybenzyl alcohol, 1,2-benzenedicarboxylic acid and pyroglutamic acid. Electron microscopy strongly supported severe destruction with punctures in V. parahaemolyticus T.11 after exposure to the LAB supernatant. In addition, W. cibaria KY10 exhibited strong auto-aggregation, hydrophobicity and tolerance to gastric juice and bile salt. Most importantly, this strain showed no haemolysis or pathogenic effects in an in vivo challenge study. These results demonstrate that W. cibaria KY10 has potential as an autochthonous probiotic for controlling V. parahaemolyticus causing AHPND in shrimp aquaculture.